Most people will just be deciding whether to stick with their current plan and any premium increases or changes in co-pay, or choosing a new one.

For some low-income seniors, that premium change may be substantial, one advocacy group said. The lowest premium plan in Georgia last year, a Humana plan, is increasing its monthly premium 42 percent, from $17.40 to $24.70 a month, said Kevin Prindiville, staff attorney for the National Senior Citizens Law Center. The lowest premium plan in Georgia next year is First Health Part D-Secure at $16.60 a month. About 33,000 people who are in a plan where they are charged no premiums are in danger of losing that, Mr. Prindiville said.

"They're going to have to switch plans in order to maintain a $0 premium," he said.

And that is still a challenge for many, said Melinda Rider, executive director of the health services center.

The problem is people can change only once a year, during this time, but the plans can change what drugs they cover or make other changes throughout the year.

Patients also don't understand how companies "tier" their payments to pay for different things at different levels, said practice manager Veronica Rogers. And some may confuse the Part D programs, in which they can keep traditional Medicare and add prescription drug coverage, and the Medicare Advantage plans, managed care plans like an HMO that handle all of their health coverage, including prescriptions.